Without delay, let's solve this. We've got 455 and we will be multiplying it by 15, that is, adding 455 to itself 15 times.
Step 1: 0 + 455 = 455
Step 2: 455 + 455 = 910
Step 3: 910 + 455 = 1365
Step 4: 1365 + 455 = 1820
Step 5: 1820 + 455 = 2275
Step 6: 2275 + 455 = 2730
Step 7: 2730 + 455 = 3185
Step 8: 3185 + 455 = 3640
Step 9: 3640 + 455 = 4095
Step 10: 4095 + 455 = 4550
Step 11: 4550 + 455 = 5005
Step 12: 5005 + 455 = 5460
Step 13: 5460 + 455 = 5915
Step 14: 5915 + 455 = 6370
Step 15: 6370 + 455 = 6825

So, 455*15 = 6825